Macrophages and related cell types play critical roles in many aspects of immunity and homeostasis and contribute to the pathogenesis of human diseases that involve chronic inflammatory responses, including atherosclerosis and diabetes mellitus. Lipid metabolism in the macrophage is subject to extreme physiological and pathophysiological programs of regulation, providing a powerful model system to explore lipidomics. Core D will contribute to each of the integrated LIPID MAPS Specific Aims as follows: Specific Aim 1: Employ lipidomics to advance mechanistic understanding of metabolism: Analyses of lipid metabolites in mouse macrophages coupled with perturbations of these cells and the mice from which they are derived will advance our mechanistic understanding of biochemical pathways. Core D will serve as a central source of macrophages for Specific Aim 1 centrally planned perturbation experiments performed by all of the Lipidomics Cores and will provide macrophages for Core-specific projects as needed. This structure will maximize uniformity of cell preparations across the Lipidomics Cores. Core D will also perform corresponding transcriptome analysis for all centrally planned lipidomics experiments to correlate changes in lipids with changes in gene expression. Specific Aim 2: Employ lipidomics to investigate macrophages and tissues under pathological conditions as disease models: Analyses of lipid metabolites in mouse cells and tissues coupled with perturbations of these cells and the mice from which they are derived will advance our understanding of interacting lipid pathways under normal and pathological conditions. Core D will serve as a central source of macrophages for the disease model studies that will be centrally planned and performed by the Lipidomics Cores. Macrophages and tissues will also be supplied for Core-specific projects as needed. Core D will perform corresponding transcriptome analysis for all centrally planned lipidomics experiments to correlate changes in lipids with changes in gene expression. Specific Aim 3: Develop lipid networks and maps from lipidomics data analysis Using transcriptomic data generated in the first two specific aims, we will contribute to new and comprehensive informatic approaches to create networks and maps of biochemical pathways and to determine the fluxes of metabolites through these pathways. Macrophages play essential roles in normal immunity, but also contribute to the development of heart disease and diabetes. The procedures and experiments performed by this Core will enable the LIPID MAPS consortium to better understand how different classes of lipids, including fat and cholesterol, are metabolized by macrophages. Knowledge gained from these studies may lead to the development of new strategies for the prevention and treatment of these diseases.